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Wang L, Wang YY, Chen ZL, Li YH. Enzymatic characterization and thermostability improvement of an acidophilic endoxylanase PphXyn11 from Paenibacillus physcomitrellae XB. Protein Expr Purif 2024; 219:106482. [PMID: 38583789 DOI: 10.1016/j.pep.2024.106482] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 03/24/2024] [Accepted: 04/04/2024] [Indexed: 04/09/2024]
Abstract
GH11 enzyme is known to be specific and efficient for the hydrolysis of xylan. It has been isolated from many microorganisms, and its enzymatic characteristics and thermostability vary between species. In this study, a GH11 enzyme PphXyn11 from a novel xylan-degrading strain of Paenibacillus physcomitrellae XB was characterized, and five mutants were constructed to try to improve the enzyme's thermostability. The results showed that PphXyn11 was an acidophilic endo-β-1,4-xylanase with the optimal reaction pH of 3.0-4.0, and it could deconstruct different kinds of xylan substrates efficiently, such as beechwood xylan, wheat arabinoxylan and xylo-oligosaccharides, to produce xylobiose and xylotriose as the main products at the optimal reaction temperature of 40 °C. Improvement of the thermal stability of PphXyn11 using site-directed mutagenesis revealed that three mutants, W33C/N47C, S127C/N174C and S49E, designed by adding the disulfide bonds at the N-terminal, C-terminal and increasing the charged residues on the surface of PphXyn11 respectively, could increase the enzymatic activity and thermal stablility significantly and make the optimal reaction temperature reach 50 °C. Molecular dynamics simulations as well as computed the numbers of salt bridges and hydrogen bonds indicated that the protein structures of these three mutants were more stable than the wild type, which provided theoretical support for their improved thermal stability. Certainly, further research is necessary to improve the enzymatic characteristics of PphXyn11 to achieve the bioconversion of hemicellulosic biomass on an applicable scale.
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Affiliation(s)
- Le Wang
- College of Life Sciences, Capital Normal University, Beijing, 100048, China.
| | - Yan Yan Wang
- College of Life Sciences, Capital Normal University, Beijing, 100048, China.
| | - Zhi Ling Chen
- College of Life Sciences, Capital Normal University, Beijing, 100048, China.
| | - Yan Hong Li
- College of Life Sciences, Capital Normal University, Beijing, 100048, China.
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Yang Y, Zhang C, Lu H, Wu Q, Wu Y, Li W, Li X. Improvement of thermostability and catalytic efficiency of xylanase from Myceliophthora thermophilar by N-terminal and C-terminal truncation. Front Microbiol 2024; 15:1385329. [PMID: 38659990 PMCID: PMC11039872 DOI: 10.3389/fmicb.2024.1385329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2024] [Accepted: 03/27/2024] [Indexed: 04/26/2024] Open
Abstract
Introduction Extracting xylanase from thermophilic filamentous fungi is a feasible way to obtain xylanase with good thermal stability. Methods The transcriptomic data of Myceliophthora thermophilic destructive ATCC42464 were differentially expressed and enriched. By comparing the sequences of Mtxylan2 and more than 10 xylanases, the N-terminal and C-terminal of Mtxylan2 were truncated, and three mutants 28N, 28C and 28NC were constructed. Results and discussion GH11 xylan Mtxylan2 was identified by transcriptomic analysis, the specific enzyme activity of Mtxylan2 was 104.67 U/mg, and the optimal temperature was 65°C. Molecular modification of Mtxylan2 showed that the catalytic activity of the mutants was enhanced. Among them, the catalytic activity of 28C was increased by 9.3 times, the optimal temperature was increased by 5°C, and the residual enzyme activity remained above 80% after 30 min at 50-65°C, indicating that redundant C-terminal truncation can improve the thermal stability and catalytic performance of GH11 xylanase.
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Affiliation(s)
- Yue Yang
- Key Laboratory of Geriatric Nutrition and Health (Beijing Technology and Business University), Ministry of Education, Beijing, China
- Beijing Engineering and Technology Research Center of Food Additives, Beijing Technology and Business University (BTBU), Beijing, China
| | - Chengnan Zhang
- Department of Exercise Biochemistry, Exercise Science School, Beijing Sport University, Beijing, China
| | - Hongyun Lu
- Key Laboratory of Geriatric Nutrition and Health (Beijing Technology and Business University), Ministry of Education, Beijing, China
- Beijing Engineering and Technology Research Center of Food Additives, Beijing Technology and Business University (BTBU), Beijing, China
| | - QiuHua Wu
- Key Laboratory of Geriatric Nutrition and Health (Beijing Technology and Business University), Ministry of Education, Beijing, China
- Beijing Engineering and Technology Research Center of Food Additives, Beijing Technology and Business University (BTBU), Beijing, China
| | - Yanfang Wu
- Key Laboratory of Geriatric Nutrition and Health (Beijing Technology and Business University), Ministry of Education, Beijing, China
- Beijing Engineering and Technology Research Center of Food Additives, Beijing Technology and Business University (BTBU), Beijing, China
| | - Weiwei Li
- Key Laboratory of Geriatric Nutrition and Health (Beijing Technology and Business University), Ministry of Education, Beijing, China
- Beijing Engineering and Technology Research Center of Food Additives, Beijing Technology and Business University (BTBU), Beijing, China
| | - Xiuting Li
- Key Laboratory of Geriatric Nutrition and Health (Beijing Technology and Business University), Ministry of Education, Beijing, China
- Beijing Engineering and Technology Research Center of Food Additives, Beijing Technology and Business University (BTBU), Beijing, China
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Kim IJ, Kim SR, Kim KH, Bornscheuer UT, Nam KH. Characterization and structural analysis of the endo-1,4-β-xylanase GH11 from the hemicellulose-degrading Thermoanaerobacterium saccharolyticum useful for lignocellulose saccharification. Sci Rep 2023; 13:17332. [PMID: 37833340 PMCID: PMC10576002 DOI: 10.1038/s41598-023-44495-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Accepted: 10/09/2023] [Indexed: 10/15/2023] Open
Abstract
Xylanases are important for the enzymatic breakdown of lignocellulose-based biomass to produce biofuels and other value-added products. We report functional and structural analyses of TsaGH11, an endo-1,4-β-xylanase from the hemicellulose-degrading bacterium, Thermoanaerobacterium saccharolyticum. TsaGH11 was shown to be a thermophilic enzyme that favors acidic conditions with maximum activity at pH 5.0 and 70 °C. It decomposes xylans from beechwood and oat spelts to xylose-containing oligosaccharides with specific activities of 5622.0 and 3959.3 U mg-1, respectively. The kinetic parameters, Km and kcat towards beechwood xylan, are 12.9 mg mL-1 and 34,015.3 s-1, respectively, resulting in kcat/Km value of 2658.7 mL mg-1 s-1, higher by 102-103 orders of magnitude compared to other reported GH11s investigated with the same substrate, demonstrating its superior catalytic performance. Crystal structures of TsaGH11 revealed a β-jelly roll fold, exhibiting open and close conformations of the substrate-binding site by distinct conformational flexibility to the thumb region of TsaGH11. In the room-temperature structure of TsaGH11 determined by serial synchrotron crystallography, the electron density map of the thumb domain of the TsaGH11 molecule, which does not affect crystal packing, is disordered, indicating that the thumb domain of TsaGH11 has high structural flexibility at room temperature, with the water molecules in the substrate-binding cleft being more disordered than those in the cryogenic structure. These results expand our knowledge of GH11 structural flexibility at room temperature and pave the way for its application in industrial biomass degradation.
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Affiliation(s)
- In Jung Kim
- Department of Food Science and Technology, Institute of Agriculture and Life Science, Gyeongsang National University, Jinju, 52828, South Korea
- Department of Biotechnology and Enzyme Catalysis, Institute of Biochemistry, University of Greifswald, Felix-Hausdorff-Str. 4, 17489, Greifswald, Germany
| | - Soo Rin Kim
- School of Food Science and Biotechnology, Kyungpook National University, Daegu, 41566, South Korea
| | - Kyoung Heon Kim
- Department of Biotechnology, Graduate School, Korea University, Seoul, 02841, South Korea
| | - Uwe T Bornscheuer
- Department of Biotechnology and Enzyme Catalysis, Institute of Biochemistry, University of Greifswald, Felix-Hausdorff-Str. 4, 17489, Greifswald, Germany
| | - Ki Hyun Nam
- College of General Education, Kookmin University, Seoul, 02707, South Korea.
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Wu Q, Zhang C, Dong W, Lu H, Yang Y, Li W, Xu Y, Li X. Simultaneously Enhanced Thermostability and Catalytic Activity of Xylanase from Streptomyces rameus L2001 by Rigidifying Flexible Regions in Loop Regions of the N-Terminus. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2023; 71:12785-12796. [PMID: 37590476 DOI: 10.1021/acs.jafc.3c03871] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/19/2023]
Abstract
The GH11 xylanase XynA from Streptomyces rameus L2001 has favorable hydrolytic properties. However, its poor thermal stability hinders its widespread application in industry. In this study, mutants Mut1 and Mut2 were constructed by rationally combining the mutations 11YHDGYF16, 23AP24/23SP24, and 32GP33. The residual enzyme activity of these combinational mutants was more than 85% when incubated at 80 and 90 °C for 12 h, and thus are the most thermotolerant xylanases known to date. The reduced flexibility of the N-terminus, increased overall rigidity, as well as the surface net charge of Mut1 and Mut2 may be partially responsible for the improved thermal stability. In addition, the specific activity and catalytic efficiency of Mut1 and Mut2 were improved compared with those of wild-type XynA. The broader catalytic cleft and enhanced flexibility of the "thumb" of Mut1 and Mut2 may be partially responsible for the improved specific activity and catalytic efficiency.
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Affiliation(s)
- Qiuhua Wu
- Ministry of Education, Key Laboratory of Geriatric Nutrition and Health (Beijing Technology and Business University), Beijing 100048, China
- China General Chamber of Commerce, Key Laboratory of Brewing Microbiome and Enzymatic Molecular Engineering, Beijing 100048, China
- School of Food and Health, Beijing Technology and Business University (BTBU), Beijing 100048, China
| | - Chengnan Zhang
- Ministry of Education, Key Laboratory of Geriatric Nutrition and Health (Beijing Technology and Business University), Beijing 100048, China
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, Beijing Technology and Business University (BTBU), Beijing 100048, China
- Beijing Association for Science and Technology-Food Nutrition and Safety Professional Think Tank Base, Beijing 100048, China
- School of Food and Health, Beijing Technology and Business University (BTBU), Beijing 100048, China
| | - Wenqi Dong
- Ministry of Education, Key Laboratory of Geriatric Nutrition and Health (Beijing Technology and Business University), Beijing 100048, China
- China General Chamber of Commerce, Key Laboratory of Brewing Microbiome and Enzymatic Molecular Engineering, Beijing 100048, China
- School of Food and Health, Beijing Technology and Business University (BTBU), Beijing 100048, China
| | - Hongyun Lu
- Ministry of Education, Key Laboratory of Geriatric Nutrition and Health (Beijing Technology and Business University), Beijing 100048, China
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, Beijing Technology and Business University (BTBU), Beijing 100048, China
- School of Food and Health, Beijing Technology and Business University (BTBU), Beijing 100048, China
| | - Yue Yang
- Ministry of Education, Key Laboratory of Geriatric Nutrition and Health (Beijing Technology and Business University), Beijing 100048, China
- China General Chamber of Commerce, Key Laboratory of Brewing Microbiome and Enzymatic Molecular Engineering, Beijing 100048, China
- School of Food and Health, Beijing Technology and Business University (BTBU), Beijing 100048, China
| | - Weiwei Li
- Ministry of Education, Key Laboratory of Geriatric Nutrition and Health (Beijing Technology and Business University), Beijing 100048, China
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, Beijing Technology and Business University (BTBU), Beijing 100048, China
- Beijing Association for Science and Technology-Food Nutrition and Safety Professional Think Tank Base, Beijing 100048, China
- School of Food and Health, Beijing Technology and Business University (BTBU), Beijing 100048, China
| | - Youqiang Xu
- Ministry of Education, Key Laboratory of Geriatric Nutrition and Health (Beijing Technology and Business University), Beijing 100048, China
- China General Chamber of Commerce, Key Laboratory of Brewing Microbiome and Enzymatic Molecular Engineering, Beijing 100048, China
- Beijing Association for Science and Technology-Food Nutrition and Safety Professional Think Tank Base, Beijing 100048, China
- School of Food and Health, Beijing Technology and Business University (BTBU), Beijing 100048, China
| | - Xiuting Li
- Ministry of Education, Key Laboratory of Geriatric Nutrition and Health (Beijing Technology and Business University), Beijing 100048, China
- China General Chamber of Commerce, Key Laboratory of Brewing Microbiome and Enzymatic Molecular Engineering, Beijing 100048, China
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, Beijing Technology and Business University (BTBU), Beijing 100048, China
- Beijing Association for Science and Technology-Food Nutrition and Safety Professional Think Tank Base, Beijing 100048, China
- School of Food and Health, Beijing Technology and Business University (BTBU), Beijing 100048, China
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5
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Huang Z, Ni D, Chen Z, Zhu Y, Zhang W, Mu W. Application of molecular dynamics simulation in the field of food enzymes: improving the thermal-stability and catalytic ability. Crit Rev Food Sci Nutr 2023:1-13. [PMID: 37485919 DOI: 10.1080/10408398.2023.2238054] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/25/2023]
Abstract
Enzymes can produce high-quality food with low pollution, high function, high acceptability, and medical aid. However, most enzymes, in their native form, do not meet the industrial requirements. Sequence-based and structure-based methods are the two main strategies used for enzyme modification. Molecular Dynamics (MD) simulation is a sufficiently comprehensive technology, from a molecular perspective, which has been widely used for structure information analysis and enzyme modification. In this review, we summarize the progress and development of MD simulation, particularly for software, force fields, and a standard procedure. Subsequently, we review the application of MD simulation in various food enzymes for thermostability and catalytic improvement was reviewed in depth. Finally, the limitations and prospects of MD simulation in food enzyme modification research are discussed. This review highlights the significance of MD simulation and its prospects in food enzyme modification.
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Affiliation(s)
- Zhaolin Huang
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, China
| | - Dawei Ni
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, China
| | - Ziwei Chen
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, China
| | - Yingying Zhu
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, China
| | - Wenli Zhang
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, China
| | - Wanmeng Mu
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, China
- International Joint Laboratory on Food Safety, Jiangnan University, Wuxi, Jiangsu, China
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Wang Q, Liu S, Li K, Xing R, Chen X, Li P. A Computational Biology Study on the Structure and Dynamics Determinants of Thermal Stability of the Chitosanase from Aspergillus fumigatus. Int J Mol Sci 2023; 24:ijms24076671. [PMID: 37047643 PMCID: PMC10095384 DOI: 10.3390/ijms24076671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2023] [Revised: 03/28/2023] [Accepted: 03/30/2023] [Indexed: 04/14/2023] Open
Abstract
Environmentally friendly and efficient biodegradation with chitosanase for degrading chitosan to oligosaccharide has been gaining more importance. Here, we studied a chitosanase from Aspergillus fumigatus with potential for production, but does not have the ideal thermal stability. The structure predicted by the Alphafold2 model, especially the binding site and two catalytic residues, has been found to have a high similarity with the experimental structure of the chitosanase V-CSN from the same family. The effects of temperature on structure and function were studied by dynamic simulation and the results showed that the binding site had high flexibility. After heating up from 300 K to 350 K, the RMSD and RMSF of the binding site increased significantly, in particular, the downward shift of loop6 closed the binding site, resulting in the spatial hindrance of binding. The time proportions of important hydrogen bonds at the binding site decreased sharply, indicating that serious disruption of hydrogen bonds should be the main interaction factor for conformational changes. The residues contributing energetically to binding were also revealed to be in the highly flexible region, which inevitably leads to the decrease in the activity stability at high temperature. These findings provide directions for the modification of thermal stability and perspectives on the research of proteins without experimental structures.
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Affiliation(s)
- Qian Wang
- CAS and Shandong Province Key Laboratory of Experimental Marine Biology, Center for Ocean Mega-Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China
- Laboratory for Marine Drugs and Bioproducts, Pilot National Laboratory for Marine Science and Technology (Qingdao), No. 1 Wenhai Road, Qingdao 266237, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Song Liu
- CAS and Shandong Province Key Laboratory of Experimental Marine Biology, Center for Ocean Mega-Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China
- Laboratory for Marine Drugs and Bioproducts, Pilot National Laboratory for Marine Science and Technology (Qingdao), No. 1 Wenhai Road, Qingdao 266237, China
| | - Kecheng Li
- CAS and Shandong Province Key Laboratory of Experimental Marine Biology, Center for Ocean Mega-Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China
- Laboratory for Marine Drugs and Bioproducts, Pilot National Laboratory for Marine Science and Technology (Qingdao), No. 1 Wenhai Road, Qingdao 266237, China
| | - Ronge Xing
- CAS and Shandong Province Key Laboratory of Experimental Marine Biology, Center for Ocean Mega-Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China
- Laboratory for Marine Drugs and Bioproducts, Pilot National Laboratory for Marine Science and Technology (Qingdao), No. 1 Wenhai Road, Qingdao 266237, China
| | - Xiaolin Chen
- CAS and Shandong Province Key Laboratory of Experimental Marine Biology, Center for Ocean Mega-Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China
- Laboratory for Marine Drugs and Bioproducts, Pilot National Laboratory for Marine Science and Technology (Qingdao), No. 1 Wenhai Road, Qingdao 266237, China
| | - Pengcheng Li
- CAS and Shandong Province Key Laboratory of Experimental Marine Biology, Center for Ocean Mega-Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China
- Laboratory for Marine Drugs and Bioproducts, Pilot National Laboratory for Marine Science and Technology (Qingdao), No. 1 Wenhai Road, Qingdao 266237, China
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Structural and biochemical analysis reveals how ferulic acid improves catalytic efficiency of Humicola grisea xylanase. Sci Rep 2022; 12:11409. [PMID: 35794132 PMCID: PMC9259647 DOI: 10.1038/s41598-022-15175-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Accepted: 06/20/2022] [Indexed: 11/13/2022] Open
Abstract
Humicolagrisea var. thermoidea is an aerobic and thermophilic fungus that secretes the GH11 xylanase HXYN2 in the presence of sugarcane bagasse. In this study, HXYN2 was expressed in Pichiapastoris and characterized biochemically and structurally in the presence of beechwood xylan substrate and ferulic acid (FA). HXYN2 is a thermally stable protein, as indicated by circular dichroism, with greater activity in the range of 40–50 °C and pH 5.0–9.0, with optimal temperature and pH of 50 °C and 6.0, respectively. FA resulted in a 75% increase in enzyme activity and a 2.5-fold increase in catalytic velocity, catalytic efficiency, and catalytic rate constant (kcat), with no alteration in enzyme affinity for the substrate. Fluorescence quenching indicated that FA forms a complex with HXYN2 interacting with solvent-exposed tryptophan residues. The binding constants ranged from moderate (pH 7.0 and 9.0) to strong (pH 4.0) affinity. Isothermal titration calorimetry, structural models and molecular docking suggested that hydrogen bonds and hydrophobic interactions occur in the aglycone region inducing conformational changes in the active site driven by initial and final enthalpy- and entropy processes, respectively. These results indicate a potential for biotechnological application for HXYN2, such as in the bioconversion of plant residues rich in ferulic acid.
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Na N, Qili M, Wu N, Sun L, Xu H, Zhao Y, Wei X, Xue Y, Tao Y. Bacterial Community and Fermentation Quality of Ensiling Alfalfa With Commercial Lactic Acid Bacterial Additives. Front Microbiol 2022; 13:836899. [PMID: 35531295 PMCID: PMC9073077 DOI: 10.3389/fmicb.2022.836899] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 02/22/2022] [Indexed: 11/13/2022] Open
Abstract
The aim of this study was to determine the effects of six common commercial lactic acid bacteria (LAB) additives [A1, Lactobacillus plantarum, L. buchneri, and Enterococcus faecalis; A2, L. plantarum and L. casei; A3, L. plantarum and L. buchneri; A4, L. plantarum, L. buchneri, L. casei, and Pediococcus acidilactici; A5, L. plantarum (producing feruloyl esterase); and A6, L. buchneri, P. acidilactici, β-glucanase, and xylanase] on the bacterial community and fermentation quality of alfalfa silage. Alfalfa was harvested at the squaring stage, wilted in the field for 24 h, and ensiled without any additives (Control) or with A1, A2, A3, A4, A5, or A6. Microbial counts, bacterial community, fermentation parameters, and nutritional composition were determined after ensiling for 90 days. The total abundance of LAB genera on alfalfa pre-ensiling was 0.38% in bacterial community. The abundances of Lactobacillus, Enterococcus, and Pediococcus in the Control silage were 42.18, 40.18, and 8.09% of abundance, respectively. The abundances of Lactobacillus in A1-, A2-, A3-, A4-, and A5-treatments were 89.32, 92.93, 92.87, 81.12, and 80.44%, respectively. The abundances of Pediococcus and Lactobacillus in A6-treatment were 70.14 and 24.86%, respectively. Compared with Control silage, LAB-treated silage had lower pH and less ammonia nitrogen and water-soluble carbohydrates concentrations (p < 0.05). Further, the A5- and A6-treatments contained lower neutral detergent fiber, acid detergent fiber, and hemicellulose than other treatments (p < 0.05). Overall, LAB genera were presented as minor taxa in alfalfa pre-ensiling and as dominant taxa in alfalfa silage. Adding LAB additives improved the fermentation quality and altered the bacterial community of alfalfa silage. The main bacterial genera in Control silage were Lactobacillus, Enterococcus, and Pediococcus. Lactobacillus dominated the bacterial communities of A1-, A2-, A3-, A4-, and A5-treatments, while Pediococcus and Lactobacillus were dominant bacterial genera in A6-treatment. Inoculating A5 and A6 degraded the fiber in alfalfa silage. It is necessary to ensile alfalfa with LAB inoculants.
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Affiliation(s)
- Na Na
- Inner Mongolia Key Laboratory of Microbial Ecology of Silage, Inner Mongolia Engineering Research Center of Development and Utilization of Microbial Resources in Silage, Inner Mongolia Academy of Agriculture and Animal Husbandry Science, Hohhot, China
| | - Moge Qili
- Inner Mongolia Key Laboratory of Microbial Ecology of Silage, Inner Mongolia Engineering Research Center of Development and Utilization of Microbial Resources in Silage, Inner Mongolia Academy of Agriculture and Animal Husbandry Science, Hohhot, China
| | - Nier Wu
- Inner Mongolia Key Laboratory of Microbial Ecology of Silage, Inner Mongolia Engineering Research Center of Development and Utilization of Microbial Resources in Silage, Inner Mongolia Academy of Agriculture and Animal Husbandry Science, Hohhot, China
| | - Lin Sun
- Inner Mongolia Key Laboratory of Microbial Ecology of Silage, Inner Mongolia Engineering Research Center of Development and Utilization of Microbial Resources in Silage, Inner Mongolia Academy of Agriculture and Animal Husbandry Science, Hohhot, China
| | - Haiwen Xu
- College of Foreign Languages, Inner Mongolia University of Finance and Economics, Hohhot, China
| | - Yi Zhao
- Inner Mongolia Key Laboratory of Microbial Ecology of Silage, Inner Mongolia Engineering Research Center of Development and Utilization of Microbial Resources in Silage, Inner Mongolia Academy of Agriculture and Animal Husbandry Science, Hohhot, China
| | - Xiaobin Wei
- Inner Mongolia Youran Animal Husbandry Co., Ltd., Hohhot, China
| | - Yanlin Xue
- Inner Mongolia Key Laboratory of Microbial Ecology of Silage, Inner Mongolia Engineering Research Center of Development and Utilization of Microbial Resources in Silage, Inner Mongolia Academy of Agriculture and Animal Husbandry Science, Hohhot, China
- *Correspondence: Yanlin Xue,
| | - Ya Tao
- Inner Mongolia Youran Animal Husbandry Co., Ltd., Hohhot, China
- Institute of Grassland Research, Chinese Academy of Agricultural Sciences, Hohhot, China
- Ya Tao,
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Wang L, Cao K, Pedroso MM, Wu B, Gao Z, He B, Schenk G. Sequence- and structure-guided improvement of the catalytic performance of a GH11 family xylanase from Bacillus subtilis. J Biol Chem 2021; 297:101262. [PMID: 34600889 PMCID: PMC8546418 DOI: 10.1016/j.jbc.2021.101262] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Revised: 09/25/2021] [Accepted: 09/27/2021] [Indexed: 12/02/2022] Open
Abstract
Xylanases produce xylooligosaccharides from xylan and have thus attracted increasing attention for their usefulness in industrial applications. Previously, we demonstrated that the GH11 xylanase XynLC9 from Bacillus subtilis formed xylobiose and xylotriose as the major products with negligible production of xylose when digesting corncob-extracted xylan. Here, we aimed to improve the catalytic performance of XynLC9 via protein engineering. Based on the sequence and structural comparisons of XynLC9 with the xylanases Xyn2 from Trichoderma reesei and Xyn11A from Thermobifida fusca, we identified the N-terminal residues 5-YWQN-8 in XynLC9 as engineering hotspots and subjected this sequence to site saturation and iterative mutagenesis. The mutants W6F/Q7H and N8Y possessed a 2.6- and 1.8-fold higher catalytic activity than XynLC9, respectively, and both mutants were also more thermostable. Kinetic measurements suggested that W6F/Q7H and N8Y had lower substrate affinity, but a higher turnover rate (kcat), which resulted in increased catalytic efficiency than WT XynLC9. Furthermore, the W6F/Q7H mutant displayed a 160% increase in the yield of xylooligosaccharides from corncob-extracted xylan. Molecular dynamics simulations revealed that the W6F/Q7H and N8Y mutations led to an enlarged volume and surface area of the active site cleft, which provided more space for substrate entry and product release and thus accelerated the catalytic activity of the enzyme. The molecular evolution approach adopted in this study provides the design of a library of sequences that captures functional diversity in a limited number of protein variants.
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Affiliation(s)
- Lijuan Wang
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, Jiangsu, China
| | - Kun Cao
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, Jiangsu, China
| | - Marcelo Monteiro Pedroso
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Brisbane, Queensland, Australia
| | - Bin Wu
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, Jiangsu, China.
| | - Zhen Gao
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, Jiangsu, China.
| | - Bingfang He
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, Jiangsu, China
| | - Gerhard Schenk
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Brisbane, Queensland, Australia
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